The invention relates to a process for producing cycloalkadienes in liquid phase by metathesis reaction of cycloalkenes in the presence of a carrier catalyst based on Re.sub.2 O.sub.7 /Al.sub.2 O.sub.3.
From GB-PS 1 105 565, the production of cyclohexadekadiene by methathesis reaction of cyclooctene on an Re.sub.2 O.sub.7 /Al.sub.2 O.sub.3 -contact is known. Preferably, this known process is carried out as a type of solids extraction in a Soxhlet apparatus. The yield is stated to come to 6% based on the amount of cyclooctene used. The type of reaction on which this process is based can be described as a dimerization of the initial product. The unsatisfactory yield can be ascribed, last but not least, to the fact that the reaction takes place with insufficient selectivity with respect to the dimerization, and also to the formation of a large proportion of higher oligomers.
It has been discovered that in the metathesis reaction of cycloalkenes, the stage of dimerization, (or, if different initial products are used, a stage conforming or equivalent to dimerization) is exceeded to a much lesser degree if the process is carried out with highly diluted solutions of the initial products.
Accordingly, it is an object of the invention to provide a novel process for producing cycloalkadienes in liquid phase by metathesis reaction of cycloalkenes in the presence of a carrier catalyst based on Re.sub.2 O.sub.7 /Al.sub.2 O.sub.3.